mbox series

[v2,0/3] xen/mm: Optimize init_heap_pages()

Message ID 20220715170312.13931-1-julien@xen.org (mailing list archive)
Headers show
Series xen/mm: Optimize init_heap_pages() | expand

Message

Julien Grall July 15, 2022, 5:03 p.m. UTC 
From: Julien Grall <jgrall@amazon.com>

Hi all,

As part of the Live-Update work, we noticed that a big part Xen boot
is spent to add pages in the heap. For instance, on when running Xen
in a nested envionment on a c5.metal with 90GB, it takes ~1.4s.

This small series is reworking init_heap_pages() to give the pages
to free_heap_pages() by chunk rather than one by one.

With this approach, the time spent to init the heap is down
to 96 ms in the setup mention above.

There is potentially one more optimization possible that would
allow to further reduce the time spent. The new approach is accessing
the page information multiple time in separate loop that can potentially
be large.

Cheers,

Julien Grall (2):
  xen: page_alloc: Don't open-code IS_ALIGNED()
  xen/heap: Split init_heap_pages() in two
  xen/heap: pass order to free_heap_pages() in heap init

 xen/common/page_alloc.c | 106 ++++++++++++++++++++++++++++++----------
 1 file changed, 79 insertions(+), 27 deletions(-)